Catheter apparatus and methods for treating vasculatures

ABSTRACT

A catheter apparatus may have a flexible shaft, guidewire lumens passing through the shaft, and a positioning device for positioning the guidewires relative to an external lumen. The positioning device may be an expansible scaffold covered with a retractable sheath. The positioning device may also be one or more balloons that are inflated through an inflation port in the shaft. The catheter apparatus may be operated by inserting a guide catheter into a vasculature with a chronic total occlusion, inserting the catheter apparatus into the guide catheter, and advancing the guidewires through the guidewire lumens and into contact with a chronic total occlusion. The positioning device may be activated before and/or between attempts to pass the guidewires through the chronic total occlusion to interrogate various parts of the chronic total occlusion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/277,962, filed May 15, 2014, which is a Continuation of U.S. patentapplication Ser. No. 13/166,623, filed Jun. 22, 2011, which issued asU.S. Pat. No. 8,764,730 on Jul. 1, 2014, which is a Divisional of U.S.patent application Ser. No. 12/147,130, filed Jun. 26, 2008, whichissued as U.S. Pat. No. 7,988,646, on Aug. 2, 2011, which claimspriority to U.S. Provisional Application No. 60/929,395, filed Jun. 26,2007, U.S. Provisional Application No. 60/960,900, filed Oct. 19, 2007,U.S. Provisional Application No. 60/996,057, filed Oct. 26, 2007, andU.S. Provisional Application No. 61/064,715, filed Mar. 21, 2008, thecontents of which are incorporated herein in their entireties.

FIELD OF THE INVENTION

The invention relates generally to an apparatus and method for treatingvasculatures, and, more particularly, to methods and apparatus forpassing one or more guidewires through a chronic total occlusion of avasculature.

BACKGROUND OF THE INVENTION

A chronic total occlusion in a coronary artery, peripheral artery, vein,dialysis fistula or other types of vasculature represents a challengefor percutaneous treatment, Percutaneous treatments are generallypreferred revascularization options as compared to bypass surgery.Continuing improvements in equipment specifically developed for chronictotal occlusions have allowed success rates to improve, Although thesuccess rates for these types of procedures have improved, theprocedures for percutaneous treatments still suffer from severaldrawbacks. Patients without a successful percutaneous treatment may needto undergo bypass surgery or experience continuing symptoms from theocclusions.

A major obstacle within a chronic total occlusion may often beencountered while attempting to advance a guidewire across the chronictotal occlusion in a vasculature. A maximum resistance may be met at themost proximal point of the lesion, i.e. the firm, fibrous cap. Whilebeing advanced, a guidewire may tend to deflect away from the fibrouscap towards the adventitial layer, often entering a false lumen. Thisoff-axis displacement of the guidewire often may result in a proceduralfailure.

Successful passage of the guidewire may also be obstructed by randomlylocated calcified regions of atherosclerotic plaque within the mass ofthe lesion. Microchannels within the obstruction may be desirabletargets for the tip of the guidewire. However, these soft spots withinthe lesion are difficult to identify angiographically and are dispersedrandomly within the matrix of the lesion.

Coronary arteries and other vasculatures tend to be non-linear conduits,often coursing over the surface of the epicardium and other tissues. Thesuccess of current technology is limited by this type of geometry. Incurrent systems, a guidewire or currently available catheter is advanceddown a vasculature to the level of the obstruction. At the point of theobstruction, the guidewire advancement may tend to proceed along theouter, greater curvature of the vasculature. Even a guidewire centeredwithin the vasculature at the proximal edge of the chronic totalocclusion may tend to proceed toward the outer, greater curvature of avasculature.

As a result, only a minor portion of the surface area of the obstructionmay be encountered with sufficient force to allow passage of theguidewire. On many occasions, the angle of encounter and/or the forceapplied to the fibrous cap may not be sufficient for crossing thefibrous cap with the guidewire. If the tip of the guidewire is curvedprior to placement through the support catheter, direct longitudinalforce may be compromised as the wire is advanced off axis. If a rapidexchange catheter system is used as catheter support, the guidewire maybuckle within the guide-catheter resulting in suboptimal longitudinalguidewire force.

At times, a single lumen angioplasty balloon may be inflated justproximal to the chronic total occlusion in an attempt to center theguidewire in the vessel lumen and provide additional support for theguidewire. Atherosclerotic lesions tend to be asymmetric with aneccentric true lumen. Therefore, attempts to limit the guidewire to thecentral axis of the vessel lumen may result in lower rates of proceduralsuccess.

Generally, needs exist for improved apparatus and methods for treatingvasculatures. More specifically, needs exist for improved apparatus andmethods for efficiently and effectively passing a guidewire through achronic total occlusion in a vasculature.

SUMMARY OF THE INVENTION

Embodiments of the present invention solve many of the problems and/orovercome many of the drawbacks and disadvantages of the prior art byproviding an apparatus and method for treating vasculatures.

In particular, embodiments of the invention may accomplish this with anapparatus for efficiently and effectively passing a guidewire through achronic total occlusion in a vasculature. The apparatus may have aflexible shaft, one or more guidewire lumens passing longitudinallythrough the shaft, and a positioning means for positioning distal endsof the one or more guidewires relative to an inner wall of an externallumen.

The positioning means may be an expansible scaffold initially in anon-expanded state. A retractable sheath may surround the expansiblescaffold and the retractable sheath may be refracted for expanding theexpansible scaffold.

The positioning means may also be one or more balloons where the one ormore balloons are inflated through an inflation port runninglongitudinally in the shaft. The positioning means may also includeguidewire lumens coupled to or otherwise disposed within the expansiblescaffold. The positioning means may also include inflatable meanssurrounding distal ends of the guidewire lumens. The inflatable meansmay or may not be located within an expansible scaffold.

The positioning means may also be a rotatable core within the shaft. Thepositioning means may also include a deflectable tip on the catheter.The positioning means may also include a shape-memory materialintegrated with the guidewire lumens.

A method of operating a catheter apparatus may include providing acatheter apparatus including a flexible shaft, one or more guidewirelumens passing longitudinally through the shaft, one or more guidewireswithin the one or more guidewire lumens, and a positioning means,inserting a guide catheter into a vasculature with a chronic totalocclusion, inserting the catheter apparatus into the guide catheter,activating the positioning means for positioning the one or moreguidewires relative to the chronic total occlusion, and advancing theone or more guidewires through the one or more guidewire lumens and intocontact with the chronic total occlusion.

The one or more guidewires may be passed through the chronic totalocclusion. The catheter apparatus may be withdrawn from the vasculaturewhile leaving the one or more guidewires in place. The one or moreguidewires may be withdrawn from contact with the chronic totalocclusion and the one or more guidewires may be advanced through the oneor more guidewire lumens into contact with the chronic total occlusionrepeatedly until a suitable site for passing the one or more guidewiresthrough the chronic total occlusion is found. The positioning means maybe activated before each advancing the one or more guidewires throughthe one or more guidewire lumens into contact with the chronic totalocclusion.

Another embodiment of the present invention may be a catheter apparatusincluding a multi-lumen main shaft; one or more guidewire lumensextending from a distal end of the multi-lumen shaft with lumens withinthe one or more guidewire lumens contiguous with at least one of themulti-lumens of the multi-lumen main shaft; an expansible supportstructure coupled to the distal end of the multi-lumen shaft; one ormore loops corresponding to each of the one or more guidewire lumens,wherein the one or more loops corresponding to each of the one or moreguidewire lumens are coupled to the expansible support structure, andwherein the one or more loops corresponding to each of the one or moreguidewire lumens project inward from the plane of the expansible supportstructure; and wherein the one or more guidewire lumens are threadedthrough the corresponding one or more loops.

Additional features, advantages, and embodiments of the invention areset forth or apparent from consideration of the following detaileddescription, drawings and claims. Moreover, it is to be understood thatboth the foregoing summary of the invention and the following detaileddescription are exemplary and intended to provide further explanationwithout limiting the scope of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate preferred embodiments of theinvention and together with the detailed description serve to explainthe principles of the invention. In the drawings:

FIG. 1A is a perspective view of a self-expanding catheter apparatus.

FIG. 1B is a distal end view of the catheter apparatus of FIG. 1A.

FIG. 1C is a cross section view of a midpoint of the catheter apparatusof FIG. 1A.

FIG. 1D is a perspective view of the self-expanding end of the catheterapparatus of FIG. 1A in an expanded state with a stop point.

FIG. 1E is a cross section view of a midpoint of the catheter apparatusof FIG. 1D.

FIG. 1F is distal end view of the catheter apparatus of FIG. 1D.

FIG. 1G is a perspective view of the self-expanding end of the catheterapparatus of FIG. 1A in an expanded state with a truncated conicalportion.

FIG. 1H is a side view of the catheter apparatus of FIG. 1A in asheathed state.

FIG. 1I is a perspective view of the catheter apparatus of FIG. 1A witha deflectable tip.

FIG. 1J is a side view of a shorter constraining sheath.

FIG. 1K is a side view of a longer constraining sheath.

FIG. 2A is a perspective view of a catheter apparatus with a singleballoon.

FIG. 2B is a cross section view of a midpoint of the catheter apparatusof FIG. 2A.

FIG. 3A is a perspective view of a catheter apparatus with doubleballoons.

FIG. 3B is a cross section view of a midpoint of the catheter apparatusof FIG. 3A.

FIG. 4A is a perspective view of a catheter apparatus with a balloon.

FIG. 4B is a distal end view of the catheter apparatus of FIG. 4A.

FIG. 4C is a cross section view of a midpoint of the catheter apparatusof FIG. 4A.

FIG. 5A is a perspective view a catheter apparatus with a rotating innercore.

FIG. 5B is a cross section view of a midpoint of the catheter apparatusof FIG. 5A.

FIG. 6A is a perspective view a catheter apparatus with a deflecting tipand stabilizing balloon.

FIG. 6B is a cross section view of a midpoint of the catheter apparatusof FIG. 6A.

FIG. 7A is a perspective view of a catheter apparatus with an expansiblemesh tip.

FIG. 7B is a detail of the catheter apparatus of FIG. 7A.

FIG. 8A is a perspective view of a catheter apparatus with guidewirelumens coupled to an expansible mesh tip.

FIG. 8B is a detail of the catheter apparatus of FIG. 8A.

FIG. 8C illustrates the retraction of a retractable sheath from thecatheter apparatus of FIG. 8A and FIG. 8B.

FIG. 8D illustrates the retraction of a retractable sheath as in FIG. 8Cwithin a vasculature.

FIG. 9A is a perspective view of a catheter apparatus with expandabledevices surrounding the lumen guidewires.

FIG. 9B illustrates the retraction of a retractable sheath from thecatheter apparatus of FIG. 9A.

FIG. 10 illustrates the retraction of a retractable sheath from acatheter apparatus with shape-memory materials integrated with guidewirelumens.

FIG. 11 illustrates the retraction of a retractable sheath from acatheter apparatus and expansion of sponges surrounding guidewirelumens.

FIG. 12A is a perspective view of a loop embodiment in an expandedstate.

FIG. 12B is an unwrapped view of the loop embodiment of FIG. 12A.

FIG. 12C is a distal end view of the loop embodiment of FIG. 12A.

FIG. 13 is an unwrapped view of another loop embodiment where loops maybe located on any closed cell.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention may include apparatus and methodsfor advancing one or more guidewires through chronic total occlusions invasculatures.

Embodiments of the present invention may incorporate several features tosuccessfully pass one or more guidewires through a chronic totalocclusion. Features of the present invention may include multiple lumensconstructed within a catheter shaft, expansion or activation of a distaltip of a catheter apparatus for creating a scaffold effect, and/ordecentralization of the guidewire lumens after activation or distalcatheter repositioning for allowing multiple sections of a fibrous capto be forcefully engaged by a guidewire. Embodiments of the presentinvention may optimize advancement of the one or more guidewires intomultiple sections of a fibrous cap of a chronic total occlusion withreasonable force.

In embodiments of the present invention one or more over-the-wire lumensmay be constructed within a shaft of a catheter apparatus. Embodimentsof the present invention may preferably use two or more lumens. Largervasculatures, such as coronary arteries, may accommodate higher profilecatheters and allow use of additional lumens. Each lumen may accommodateat least a 0.014″ diameter guidewire. Other sized lumens and guidewiresmay be accommodated based upon the desired end use. Standardoff-the-shelf or customized guidewires may be used. For example, inaddition to traditional guidewires, embodiments of the present inventionmay be used with guidewires including, but not limited to, steerable,hydrophilic, Teflon-coated, heparin-coated, ball-tip, J-tip, spiral tip,angulated wire and others.

Embodiments of the present invention may be combined with other types ofdevices. The positioning systems and methods of the present inventionmay be to deliver and/or catheter direct other catheters towards adesired position. For example, a vibrating catheter or other specializedcatheter may be directed towards a chronic total occlusion or otherlocation in a vasculature. A microcatheter with a distal positioningdevice, including, for example, one or more balloons that may beinflated individually, sequentially or simultaneously, or otherfeatures, may be placed in proximity to a chronic total occlusion. Apositioning system may steer the microcatheter away from a wall of avessel, as it probes a cap of a chronic total occlusion. Microcatheterswith angulation or other features may be placed in proximity to achronic total occlusion where the angulation steers away from a wall ofa vessel, probes a cap of a chronic total occlusion or otherwise changesdirections. A catheter portion and/or sheath of embodiments of thepresent invention may be large enough to deliver and/or positionspecialized catheters to a desired location. Positioning devices maythen be used to position the specialized catheters in a beneficialmanner for a procedure.

In particular, embodiments of the present invention may deliver energyvia the guidewires through radio frequencies and/or lasers. Furthermore,other types of energy may be delivered such as direct conductive heatenergy, infrared or other types of energy that may be useful inparticular applications. Various types of guidewires and/or deliveringenergy via guidewires may allow for various types of treatments. Theexternal diameter of a catheter apparatus of the present invention mayallow passage through a standard guide catheter. The outer surface of acatheter apparatus of the present invention may be coated withhydrophilic material to allow easier passage through the guide catheter.With alternate dimensions, the catheter apparatus of the presentinvention may be used in peripheral vessels. In this situation, a guidecatheter may not be necessary to insert the device into the vasculature.

FIGS. 1A-1K show a self-expanding catheter apparatus 11. The externaldiameter of the self-expanding catheter apparatus 11 may pass through asheath 19.

The sheath 19 may be a separate element surrounding the distal end ofthe catheter apparatus 11 to maintain the catheter apparatus 11 in aninactive state. The sheath 19 may have a rounded or tapered end forfacilitating passage through a vasculature. Other end configurations arepossible depending on particular uses.

Additional embodiments of the sheath may be shown in FIGS. 1J-1K. Asheath 68, 69 may be used to lower a profile of a self-expanding distalportion 13 of the catheter apparatus 11, which may preferably be anitinol component, during insertion and removal of the catheterapparatus 11 from a vasculature. A sheath 68 may have a shorterconfiguration, as shown in FIG. 1J, covering at least a distalself-expanding component, preferably a nitinol element, on the catheterapparatus 11. The sheath 68, however, may preferably be long enough tocorrespond to the length of the treated vasculature, i.e., long enoughto cover the portion of the catheter extending outside of a guidecatheter and into the vasculature. This sheath configuration mayfunction by insertion through a guide catheter and advancement into atreated vasculature. The sheath 68 may be attached 60 to a solid coreguidewire and/or flexible device 67. The solid core guidewire and/orflexible device 67 may be long enough to traverse a guide catheter. Thesolid core guidewire and/or flexible device 67 may be a solid structurewith no internal lumens and may preferably be made of plastic or similarmaterials. The solid core guidewire and/or flexible device 67 may bemanipulated from outside the body, preferably by means of an expandedelement 64 at a proximal end of the solid core guidewire and/or flexibledevice 67. The solid core element 67 may parallel the catheter apparatus11 through a guide catheter. A distal portion 58 of the sheath 68 may beflared to fit a self-expanding portion 13 of the catheter apparatusdevice 11. The distal portion 58 may also have one or more radiopaque orother types of markers 54. The sheath 68 may have a stop point to allowwithdrawal of the sheath 68 to a predetermined position, which may alsofacilitate resheathing of the catheter apparatus 11.

Alternatively, as shown in FIG. 1K, a sheath 69 may have a longerlength, completely surrounding an intravascular portion of the catheterapparatus 11 during insertion and removal. The sheath 69 may be aflexible with a roughly cylindrical shape. The sheath 69 may preferablybe made of plastic or other similar materials. This sheath configurationmay have a larger profile element 62 at an extra-vascular, proximal end,allowing for easier handling and movement of the sheath 69. A distalportion 66 of the sheath 69 may be flared to fit a self-expandingportion 13 of the catheter apparatus device 11. The distal portion 66may also have one or more radiopaque or other types of markers 56. Thesheath 69 may have a stop point to allow withdrawal of the sheath 69 toa predetermined position, which may also facilitate resheathing of thecatheter apparatus 11. The sheath 69 may be used in conjunction with aguide catheter or may function without a guide catheter in anon-coronary vasculature.

A body or shaft 23 of the catheter apparatus 11 may be made of aflexible plastic material or any other similar substance. A hydrophiliccoating may or may not be added to the outer surfaces of the catheterapparatus 11. One or more hubs 21 corresponding to one or moreguidewires 15 and one or more lumens 17 may be disposed at a proximateend 29 of the catheter apparatus 11.

The one or more hubs 21 may be marked, color-coded, numbered or mayotherwise differentiate between one another. Identification ofindividual guidewire lumens may allow more effective use of embodimentsof the present invention. With marking, users may improve their abilityto identify which guidewire lumen may be preferably used during aprocedure. For example, if a particular guidewire lumen is in apreferable location relative to other guidewire lumens an operator maydesire a quick and reliable method of inserting a guidewire through thatparticular guidewire lumen. Marking may save time and effort byeliminating trial and error to determine a desired guidewire lumen.Alternatively, marking may be useful for applications other thantreatment of occluded vasculatures, such as steering guidewires throughvasculatures via various lumens. For example, marking can allowembodiments of the present invention to be used in other areas and/orconditions of a vasculature, such as traversing the tortuous coronaryarteries. Distal and proximal ends of the guidewire lumens may besimilarly marked to identify the guidewire lumens. Distal ends orstructures on distal ends of the guidewire lumens may be marked suchthat the user may identify a preferred guidewire lumen while thecatheter apparatus is within a patient. Marking with radiopaque or othertypes of markers may include temporary structures within the guidewirelumens. For example, markers may be present on stylets within theguidewire lumens. The stylets may be removed if desired to reduce massor otherwise improve efficiency of a procedure.

The one or more hubs 21 may allow introduction of stylets or otherstructures that run through the catheter apparatus to render it stiff orto remove debris from its lumen. The one or more hubs 21 may also allowpassage of one or more guidewires 15.

Generally, a distal portion 13 of the catheter apparatus 11 may functionas a scaffold-type structure. The distal portion 13 of the catheterapparatus 11 may stabilize the catheter apparatus 11 within avasculature lumen as one or more guidewires 15 are advanced into achronic total occlusion. One or more guidewires 15 may be threadedthrough one or more lumens 17 within the catheter apparatus 11. Thedistal portion 13 of the catheter apparatus 11 is preferablyself-expanding. FIG. 1B shows the distal end 25 of the catheterapparatus 11 in an expanded state. FIG. 1C shows a cross section of thecatheter apparatus 11 with a retractable sheath 19 surrounding the body23. The retractable sheath 19 may be retracted by moving the retractablesheath towards the proximate end 29 of the catheter apparatus 11. Thedistal portion 13 of the catheter apparatus 11 may include an activatedscaffold structure 27 to stabilize the catheter apparatus 11. Theactivated scaffold structure 27 may expand to match a diameter of thevasculature lumen upon retraction of the retractable sheath 19.

Nitinol and/or stainless steel may be incorporated into the scaffoldstructure 27. Nitinol is an illustrative example of a shape memoryalloy. Other shape memory alloys or other similar substances may beused. Generally, after a sample of a shape memory alloy has beendeformed from its original crystallographic configuration, the shapememory alloy regains its original geometry by itself. This property ofshape memory alloys may allow for expansion of the scaffold structure 27after retraction of the retractable sheath 19. The nitinol and/orstainless steel scaffold structure 27 may create a stent-like mesh. Thescaffold structure 27 may form the surface of the distal portion 13 ofthe catheter apparatus 11.

FIG. 1H shows an inactive scaffold structure 31. The inactive scaffoldstructure 31 may be advanced over a guidewire into a chronic totalocclusion with a retractable sheath 19 in place to constrain theself-expanding but inactive scaffold structure 31. The retractablesheath 19 may cover the inactive scaffold structure 31. When theinactive scaffold structure 31 is properly positioned, the retractablesheath 19 may be refracted by an appropriate retraction means. As theretractable sheath 19 is retracted, the inactive scaffold structure 31of the catheter apparatus 11 may become active and may flare out. Duringa flare out process, the inactive scaffold structure 31 may self-expandto assume a larger diameter to roughly approximate the diameter of thevasculature in the location of the distal portion 13 of the catheterapparatus 11.

The retraction of the retractable sheath 19 may be a continuous orstep-wise process. For example, the retractable sheath 19 may beretracted in one operation by a user until the scaffold structure 31 isfully exposed. Alternatively, the retractable sheath 19 may be retractedin increments less than that required for full expansion of the scaffoldstructure 31. Stop points during retraction of the retractable sheath 19may allow for predetermined quantities of expansion of the scaffoldstructure 31. For example, if a procedure required less than fullexpansion of the scaffold structure 31, a stop point short of fullretraction of the retractable sheath 19 may be chosen.

The conversion and expansion of the inactive scaffold structure 31 intoan active scaffold structure 27 may create a relatively stable platformfrom which to advance the one or more guidewires 15 into multiplesections of the chronic total occlusion. The activated catheterapparatus 11 with the retractable sheath 19 retracted may have anactivated scaffold structure shaped as a truncated cone or othersuitable shape. A surface 33 of the expanded distal end 13 of thecatheter apparatus 11 may consist of a “skin” of the scaffold structure27. An end cap 35 may or may not cover the distal end 35 of the catheterapparatus 11. The end cap 35 may preferably be made of an imperviousexpandable polymer, but other similar substances may be used.

FIG. 1D shows an activated scaffold structure 27 that may be filled withan expandable polymer or similar material. The expandable polymer orsimilar material may fill the scaffold structure 27 to form a truncated,conical or other appropriate shape for securing the catheter apparatus11 within the vasculature lumen. The expandable polymer may supportdistal portions of one or more guidewire lumens 17. Upon expansion ofthe expandable polymer, the embedded lumen ends 37 may flare outcorrespondingly with the end cap 35. FIG. 1E shows a cross section ofthe catheter apparatus 11 with the retractable sheath 19 surrounding theshaft 23. FIG. 1F shows an end view of the expanded end cap 35 withembedded guidewire lumens 17.

A skin 33 may surround the expandable polymer or similar material. Theskin 33 may be a temporary metal “stent”. The metal stent may be a meshtype structure. The metal stent may become a truncated conical shapeafter expansion or any other suitable shapes.

The a-b dimension 39 indicated in FIG. 1D may shorten when theretractable sheath 19 is removed from scaffold structure 27. The degreeof shortening of the a-b dimension 39 may vary depending on the degreeof expansion, the materials used, etc.

The retractable sheath 19 may be refracted to a stop point. The stoppoint may prevent over-retraction of the retractable sheath 19. Aretractable sheath 19 at the stop point may facilitate re-sheathing ofthe scaffold structure 27.

FIG. 1G shows multiple guidewire lumens 17 that may be suspended withina scaffold structure 27 without using an expansible polymer or similarfiller. A skin 33 may be made of nitinol, stainless steel, or anotherexpansible substance. The one or more guidewire lumens 17 may extend tothe distal end 25 of the scaffold structure 27. The scaffold structure27 may begin roughly at a transition point 41. The one or more guidewirelumens 17 may or may not be embedded in an end cap 35. The end cap mayan impervious plastic material.

FIG. 1I shows a catheter apparatus with an expandable skin 33 and adeflectable tip 43. The deflectable tip 43 may be rotatable or otherwisemoveable. The deflectable tip 43 may be rotatable with a rotator 45 orother similar device at the proximate end 29 of the catheter apparatus11. The embodiment depicted in FIG. 1I preferably does not include andend cap 35. The lack of an end cap 35 may allow for freedom of movementof the deflectable tip 43. The distal portion 13 of the catheterapparatus 11 may flare after the retractable sheath 19 is retracted. Asingle, centrally located deflectable lumen 47 may allow a guidewire 15to be advanced in numerous planes. The deflectable tip 43 may allow forcontrolled probing of the fibrous cap of a chronic total occlusion.

Other embodiments of the present invention may include one or moreballoons at or near a distal end of a catheter apparatus. The one ormore balloons may be circumferential. Alternatively, the one or moreballoons may be offset and placed longitudinally. Other positions andarrangements are possible depending on particular situations.

FIG. 2A shows an embodiment of the present invention with a balloon 53that may be placed longitudinally near a distal tip 55 of a catheterapparatus 51. The balloon 53 may parallel the long axis of a shaft 59 ofthe catheter apparatus 51. Inflation of the balloon 53 may deflect theposition of one or more guidewire lumens 57 relative to the fibrous capof a chronic total occlusion. The balloon 53 may be inflated to adiameter that may buttress the catheter apparatus 51 against a wall ofthe vasculature lumen. The balloon 53 may then be deflated, the catheterapparatus 51 rotated, and the balloon 53 reinflated.

FIG. 2B shows a cross section of the catheter apparatus 51. The balloon53 may be inflated and deflated through an inflation port 65. Theinflation port 65 may pass through the shaft 59 to connect the balloon53 to a proximate end 63 of the catheter apparatus 51. This method mayresult in one or more guidewires 59 probing various sections of thefibrous cap. One or more hubs 61 at the proximate end 63 of the catheterapparatus 51 may allow passage of the one or more guidewires 59. Styletsor other similar structures may be inserted or reinserted into thecatheter apparatus 51 to facilitate rotation.

FIG. 3A shows an embodiment of the present invention with a firstlongitudinal balloon 73 and a second longitudinal balloon 75 positionednear a distal end 77 of a catheter apparatus 71. More balloons may beused for additional or different control of the catheter apparatus. Themultiple balloons 73, 75 may be inflated individually, simultaneously,alternatively or sequentially depending on the particular circumstances.The pattern of inflation and/or deflation of the multiple balloons 73,75 may allow redirection of a distal catheter tip 79 relative to afibrous cap of a chronic total occlusion. Repositioning of the distalcatheter tip 79 may permit more complete interrogation of the fibrouscap with one or more guidewires 81. One or more hubs 83 at the proximateend 85 of the catheter apparatus 71 may allow passage of the one or moreguidewires 81 through a shaft 87.

FIG. 3B shows a cross section of the catheter apparatus 71. One or moreguidewire lumens 89 may pass through the catheter apparatus 71.Embodiments of the present invention may be constructed with multipleinflation ports (not shown) or with one inflation port 91 servicing themultiple balloons 73, 75. If the later option is utilized, the balloonmaterials may be constructed to allow selective, and/or sequentialinflations at increasing balloon pressures. The balloons 73, 75 may bepositioned at various angles relative to one another around thecircumference of the shaft 87.

FIG. 4A shows an embodiment of the present invention with a balloon 103with a distal surface 105 in a catheter apparatus 101. The balloon 103may be flat, cylindrical or any other suitable configuration.Additionally, the balloon 103 may be sectioned. One or more guidewirelumens 107 may be extruded through the balloon material. The balloon 103may be inflated to match the inner diameter of the vasculature lumen.FIG. 4B shows an end view of the catheter apparatus 101. As the balloon103 expands, the one or more guidewire lumens 107 extruded through theballoon 103 may diverge relative to one another in reaction to expansionof the balloon 103. The divergence may allow one or more guidewires 109to probe various sections of the fibrous cap of the chronic totalocclusion. One or more hubs 111 at the proximate end 113 of the catheterapparatus 101 may allow passage of the one or more guidewires 109. FIG.4C shows a cross section of the catheter apparatus 101. A ballooninflation port 115 may pass through a shaft 117 with the one or morelumens 107 to inflate and/or deflate the balloon 103.

FIG. 5A shows a catheter apparatus 121 with an inner core 123 within anouter core 125. The inner core 123 may contain one or more lumens 127.Embodiments of the present invention may preferably include two or morelumens 127. FIG. 5B illustrates an embodiment with two lumens placed atpositions of 3 o'clock and 9 o'clock within the inner core 123. Otherquantities of lumens 127 and positions are contemplated for variousapplications and situations. The inner core 123 may be rotated withinthe outer shell 125 of the catheter apparatus 121 by turning orotherwise manipulating a rotator 129 at a proximate end 131 of thecatheter apparatus 121. The rotator 129 may be coupled 133 or otherwiseconnected to the inner core 123. One or more guidewires 135 may beconnected to one or more hubs 137 at the proximate end 131 of thecatheter apparatus 121. The one or more guidewires may extend from adistal end 139 of the catheter apparatus 121.

A rotatable inner core 123 of catheter apparatus 121 may be used inconjunction with the various balloon configurations described above. Forexample, if constructed with a non-longitudinal stabilizing balloon, theshape of the distal tip balloon may be circumferential, i.e.,doughnut-shaped.

FIG. 6A shows an embodiment of the present invention with a singlestabilizing balloon 143 and a deflecting tip 145 on a catheter apparatus141. The single stabilizing balloon 143 may be used in conjunction witha deflectable distal catheter tip 145 for eccentric placement of one ormore guidewires 147. The one or more guidewires 147 may be passedthrough one or more hubs 149 at a proximate end 151 of the catheterapparatus 141. FIG. 6B shows a cross section of the catheter apparatus141. One or more lumens 153 may pass through a shaft 155. An inflationport 157 may allow inflation and/or deflation of the stabilizing balloon143. The deflecting tip 145 may be located at various angles dependingon the particular situation.

Catheter apparatus shafts 23, 59, 87, 117, 12 and 155 may be constructedwith either a circular, oval or rectangular shape. Other shapes arepossible depending on particular uses.

FIG. 7A shows an embodiment of the present invention with an expansibleportion 159 at a distal tip 161 of a catheter apparatus 163. Theexpansible portion 159 may be a mesh or other similar configuration asdescribed above. The expansible portion 159 may be expanded byretracting a retracting sheath 165 away from the distal tip 161 of thecatheter apparatus 163. The expansible portion 159 may be expanded intocontact with a wall of a vasculature.

FIG. 7B shows a detail of the catheter apparatus 163. A central core 167may contain one or more guidewire lumens 169. The central core 167 mayor may not be expandable. The central core 167 may be rotatable to allowone or more guidewires 169 to probe various sections of a fibrous cap.One or more hubs 171 at the proximate end 173 of the catheter apparatus163 may allow passage of the one or more guidewires 169.

FIG. 8A shows an embodiment of the present invention with an expansibleportion 175 at a distal tip 177 of a catheter apparatus 179. Theexpansible portion 175 may be a mesh or other similar configuration asdescribed above. The expansible portion 175 may be expanded byretracting a retracting sheath 181 away from the distal tip 177 of thecatheter apparatus 179. The expansible portion 175 may be expanded intocontact with a wall of a vasculature. One or more hubs 185 at theproximate end 187 of the catheter apparatus 179 may allow passage of theone or more guidewires 189.

FIG. 8B shows a detail of the catheter apparatus 179. One or moreguidewire lumens 183 may be formed of extruded plastic or similarmaterials. The figures generally illustrate three guidewire lumens 183,but other numbers and configurations may be desirable depending onparticular uses. The one or more guidewire lumens 183 may haveshape-memory alloys or other similar materials integrated into,surrounding or within the structure of the one or more guidewire lumens183. Preferably, the one or more guidewire lumens 183 may self-expandupon retraction of the retraction sheath 181 such that ends 182 of theone or more guidewire lumens are spaced apart and approximately halfwaybetween the center point and the inner surface of a vasculature. The oneor more guidewire lumens 183 may be configured to expand into variouspredetermined positions and configurations depending on particularapplications. For example, FIG. 8B shows a triangular configuration forthe guidewire lumens 183. Other configurations are possible using threeguidewire lumens 183. Furthermore, different numbers of guidewire lumensmay be used in various configurations. Alternatively, the one or moreguidewire lumens 183 may be coupled to an inner surface of theexpansible portion 175. The one or more guidewire lumens 183 may beadhered or integrally molded to the inner surface of the expansibleportion 175.

Expansion of the expansible portion 175 may cause the one or moreguidewire lumens 183 to separate via a self-expanding shape-memorymaterial. Alternatively, the one or more guidewire lumens 183 may not becoupled to the expansible portion 175 but may instead be positionedwithin the internal volume of the expansible section 175 to allowprobing of a fibrous cap. Additionally, a self-expanding polymer mayfill the expansible portion 175. In an initial configuration theself-expanding polymer may be in a compressed state. As the expansibleportion 175 is released from the retracting sheath 181, theself-expanding polymer may expand as well. The one or more guidewirelumens 183 may be embedded in the self-expanding polymer and may bemoved into a desired position by the expansion of the self-expandingpolymer. The self-expanding polymer may expand by absorbing moisture orblood from within the vasculature or through other expansion mechanisms.The self-expanding polymer may then be removed after a procedure.

FIG. 8C illustrates the operation of the catheter apparatus 179 of FIG.8A and FIG. 8B. Similar operational procedures may be used for otherembodiments described herein. Step 1 of FIG. 8C shows the catheterapparatus 179 in an initial state with a retractable outside sheath 181moved as far as possible distally from a guidewire lumen tube 191. Steps2-7 show incremental stages of retraction of the retractable outsidesheath 181. As the retractable outside sheath 181 is refracted back overthe guidewire lumen tube 191, the expansible portion 175 isincrementally exposed and allowed to expand. As the expansible portion175 expands the one or more guidewire lumens 183 separate and are heldin a desired position by the shape-memory allow materials or by couplingto the expansible portion 175. Step 7 shows the expansible portion 175in a fully deployed state. The end view of FIG. 8C shows the one or moreguidewire lumens 183 in the fully deployed state. Step 8 shows aguidewire 189 inserted through a guidewire lumen 183. FIG. 8Dillustrates the operation of the catheter apparatus 179 as shown in FIG.8C within a vasculature 184 with an occlusion 186.

FIG. 9A shows an embodiment of the present invention with one or moreinflatable devices 193 surrounding one or more guidewire lumens 195within an expansible portion 197 of a catheter apparatus 199. Theexpansible portion 197 may be a mesh or other similar configuration asdescribed above. The expansible portion 197 may be expanded byretracting a retracting sheath 201 away from a distal tip 203 of thecatheter apparatus 199. The expansible portion 197 may be expanded intocontact with a wall of a vasculature. The expansible portion 197 may beomitted as shown in FIG. 9B.

The inflatable devices 193 may initially be in a deflated conditionduring insertion and positioning of the catheter. The inflatable devices193 preferably are balloons, but may be any other expansible type ofdevice. The balloons may surround the outer surface of the one or moreguidewire lumens 195. The balloons may be cylindrical or other shapes toposition the one or more guidewire lumens 195 within the expansibleportion 175. The inflatable devices 193 may include one balloon for eachguidewire lumen 195 or one balloon may correspond to several guidewirelumens 195. For example, a single inflatable device 193 may be inflatedto separate all of the guidewire lumens 195. Alternatively, two separateinflatable devices 193 may be used to separate three or more guidewirelumens. The inflatable devices 193 may be bifurcated or trifurcateddepending on the number of guidewire lumens 195 and the particularapplication. The expansible sheath 197 may assist in containingmultiple, separate inflatable devices 193, but may not be essential tothe operation of the present invention.

One or more ports (not shown) may allow inflation or one or more of theinflatable devices 193 depending on the number of separate inflatabledevices 193. For example, one port may be used to inflate one inflatabledevice 193. Alternatively, if two or more separate inflatable devices193 are present, then two or more ports may be used to inflate anddeflate the inflatable devices 193 serially or in parallel depending ona particular use or condition. Different numbers and combinations ofinflatable devices and ports may be possible. Inflation of variouscombinations of inflatable devices 193 with various numbers andconfigurations of ports may allow for probing of a fibrous cap. If endsof the one or more guidewire lumens 195 or the inflatable devices 193themselves are marked, a user may inflate specific inflatable devices193 but not others to more accurately interrogate an occlusion. Each ofthe inflatable devices 193 may be inflated into contact with theexpanded expansible portion 197 to secure the position of the one ormore guidewire lumens 195. Guidewires (not shown) may then be passedthrough the one or more guidewire lumens 195. The inflatable devices 193may be deflated prior to withdrawing the catheter apparatus 199.

As shown in FIG. 9B an embodiment of the present invention may includethe inflatable devices 193 without the expansible portion 197, as shownin FIG. 9A. The inflatable devices 193 may be exposed by withdrawing theretracting sheath 201. Particularly if the inflatable devices 193 areunitary, the expansible portion 197 may not be needed. However, even ifthe inflatable devices 193 are separate the expansible portion 197 maybe omitted.

Step 1 of FIG. 9B shows the catheter apparatus 199 in an initial statewith a retractable outside sheath 201 moved as far as possible distallyfrom a guidewire lumen tube 205. Steps 2-4 show incremental stages ofretraction of the retractable outside sheath 201 to expose the one ormore guidewire lumens 195 with corresponding inflatable devices 193.Steps 5-6 show incremental stages of inflation of the inflatable devices193 into a final position with a vasculature 209 with an occlusion 211.Step 7 shows the catheter apparatus 199 in a fully deployed state. Step8 shows a guidewire 207 inserted through a guidewire lumen 195.

FIG. 10 illustrates operation of a catheter apparatus 213 that mayinclude shape-memory materials integrated with the one or more guidewirelumens 217. Preferably, the one or more guidewire lumens 217 may beconstructed out of extruded plastic or other similar materials.Shape-memory or other expansible materials may be integrated into,surround, be contained within or reinforce the one or more guidewirelumens 217.

Step 1 of FIG. 10 shows the catheter apparatus 213 in an initial statewith a retractable outside sheath 215 moved as far as possible distallyfrom a guidewire lumen tube 215. The one or more guidewire lumens 217may be exposed by withdrawing the retracting sheath 215 from the distalend of a catheter apparatus 213 as shown in Steps 2-6. The one or moreguidewire lumens 217 may then assume a final spaced or relaxedconfiguration as shown in Step 7. The guidewire lumens may move outwardrelative to one another a desired distance and/or into contact withinner walls of a vasculature 219 with an occlusion 221. A guidewire 223may then be threaded through the one or more guidewire lumens 217 asshown in Step 8. After completion of a procedure, the retracting sheath215 may be advanced towards the distal end of the catheter apparatus tocompress the one or more guidewire lumens 217 into a compact arrangementfor removal from the vasculature 219. Alternatively, the one or moreguidewire lumens 217 may be withdrawn into the distal end of theretracting sheath 215 before removal from the vasculature 219.

FIG. 11 illustrates operation of a catheter apparatus 225 withexpansible devices 227 surrounding one or more guidewire lumens 229.Preferably, the expansible devices 227 are sponges or other materialsthat expand within the vasculature without input from a user. Eachguidewire lumen 229 may have a separate expansible device 227 ormultiple guidewire lumens may be incorporated into one expansible device227.

Step 1 of FIG. 11 shows the catheter apparatus 225 in an initial statewith a retractable outside sheath 231 moved as far as possible distallyfrom a guidewire lumen tube 233. The one or more guidewire lumens 229may be exposed by withdrawing the retracting sheath 231 from the distalend of a catheter apparatus 225 as shown in Steps 2-6. As the retractingsheath 231 is withdrawn from the expansible devices 227, the expansibledevices 227 begin to expand. If the expansible devices 227 are sponges,the expansible devices 227 may absorb moisture from the vasculature toincrease in volume. The one or more guidewire lumens 229 may then assumea final expanded configuration as shown in Step 7. The guidewire lumens229 embedded with the expansible devices 227 may move outward relativeto one another a desired distance and/or into contact with inner wallsof a vasculature 233 with an occlusion 235. A guidewire 237 may then bethreaded through the one or more guidewire lumens 229 as shown in Step8. After completion of a procedure, the retracting sheath 231 may beadvanced towards the distal end of the catheter apparatus 225 tocompress the one or more guidewire lumens 229 into a compact arrangementfor removal from the vasculature 233. Alternatively, the one or moreguidewire lumens 229 may be withdrawn into the distal end of theretracting sheath 231 before removal from the vasculature 233. Movementof the retracting sheath 231 may compress the expansible devices 227into a position suitable for removal from the vasculature 233. If theexpansible devices 227 are sponges, the compression may force moistureout of the sponges.

Generally, after crossing a chronic total occlusion with a guidewire,the catheter apparatus may be resheathed and removed from thevasculature. The guidewire may be left in position.

One or more guidewires preferably remain in or near the longitudinalaxis of the corresponding support catheter lumen. This positioning ofthe one or more guidewires may optimize the force of the one or moreguidewires when engaged with the fibrous cap of the chronic totalocclusion. Multiple eccentrically located guidewire lumens may improvethe chance of success in passing one or more guidewires through achronic total occlusion. The mass of the multi-lumen support cathetermay provide additional support for the guidewire and prevents off-axis,i.e., lateral, displacement of portions of the one or more guidewireslocated in the guide catheter and in the vasculature. Eccentricdistribution of the one or more guidewire lumens may allow engagement ofmultiple, eccentric sections of the fibrous cap. Embodiments of thepresent invention may permit simultaneous placement of multipleguidewires. Multiple guidewires may enhance available techniques such as“parallel guidewire” and “see-saw” wire.

FIG. 12A shows a catheter apparatus 241 with guidewire lumens 243, 245,247 passing through loops 249, 251, 253, 255, 257, 259. The number andconfiguration of the loops or guidewire lumens 243, 245, 247 may bevariable. Alternative numbers and configurations are possible. Guidewirelumens 243, 245, 247 may be guided into a predetermined position duringexpansion of an expansible support structure 261 by threading theguidewire lumens 243, 245, 247 through the inwardly projecting loops249, 251, 253, 255, 257, 259. Loops 249, 251, 253, 255, 257, 259 may becoupled to the expansible support structure 261. FIGS. 12A-12Cillustrate an embodiment of the present invention where each guidewirelumen 243, 245, 247 may pass through two loops 249, 251, 253, 255, 257,259. Alternative embodiments may only use one loop for each guidewirelumen. Still other alternative embodiments may use three or more loopsfor each guidewire lumen. The operation of the loops and guidewirelumens in FIGS. 12A-12C are illustrative of the alternative embodiments.The guidewire lumens 243, 245, 247 are guided into position by passingthrough the loops 249, 251, 253, 255, 257, 259. The expansible supportstructure 261 may be coupled to a main multi-lumen shaft 263 by anyconventional means such as adhesive, welding, etc. In the currentembodiment of the invention, three guidewire lumens 243, 245, 247 areshown, but other numbers and configurations of lumens may be provided. Asheath 265 may hold the expansible support structure 261 in a compressedstate prior to deployment of the expansible support structure 261.

FIG. 12B shows a flat projection of the expansible support structure 261with loops 249, 251, 253, 255, 257, 259. FIGS. 12A-12C show a fiveclosed-cell configuration. Embodiments of the present invention mayinclude different quantities of closed-cells depending on desiredapplications. FIG. 12B shows a first closed cell 265, a first connectorregion 267, a second closed cell 269, a second connector region 271, athird closed cell 273, a third connector region 275, a fourth closedcell 277, a fourth connector region 279, and a fifth closed cell 281. InFIG. 12B, the first closed cell 265 may be at a distal end of thecatheter apparatus 241 and the firth closed cell 281 may located towardsa proximal end of the catheter apparatus 241. In each closed cell,struts 283 may form a zigzag pattern to support the catheter apparatus241. Connectors 285 residing in the first connector region 267 mayconnect the first closed cell 265 to the second closed cell 269 bylinking strut intersections 287 on the first closed cell 267 with strutintersections 289 on the second closed cell 271. Connectors 285 may bethinner than struts 283 and the angular relationship between struts 283and connectors 285 may change during expansion and compression of theexpansible support structure 261. Similar structures and interactionsmay be found in and between the remaining closed cells.

Loops 249, 251, 253, 255, 257, 259 may be located at strut intersections291. Loops 249, 251, 253, 255, 257, 259 may be coupled to the strutintersections 291 by loop supports 293. Loop supports 293 may be taperedto reduce stress on the apparatus. Struts 283 may also be tapered toreduce stress on the apparatus. The loop supports 293 may be positionedat other locations along the struts 283 or connectors 285 if desired.Loops 249, 251, 253, 255, 257, 259 and inner shape cutouts may becircular, oval, oblong or any additional shapes to allow the guidewirelumens 243, 245, 247 to slide within the loops 249, 251, 253, 255, 257,259. Shapes other than circles may be beneficial when the loops 249,251, 253, 255, 257, 259 lie at an angle other than perpendicular to thecylindrical plane of the expansible support structure 261. Loops 249,251, 253, 255, 257, 259 may be shaped to correspond to guidewire lumens243, 245, 247 and allow the guidewire lumens 243, 245, 247 to slidethrough the loop openings.

Each guidewire lumen 243, 245, 247 may pass through two loops in theembodiment of FIGS. 12A-12C. For example, guidewire lumen 243 may passthrough loops 249 and 251, guidewire lumen 245 may pass through loops253 and 255, and guidewire lumen 247 may pass through loops 257 and 259.Passing the guidewire lumens 243, 245, 247 through the loops 249, 251,253, 255, 257, 259 may position the guidewire lumens 243, 245, 247 in adesired position within the expansible support structure 261. Asindicated above, other numbers and configurations of loops are possible.

To prevent twisting and damage to the guidewire lumens 243, 245, 247,the loops 249, 251, 253, 255, 257, 259 for each guidewire lumen arepreferably located on every other closed cell. As shown in FIG. 12B, theloops 249, 251, 253, 255, 257, 259 are located on the first closed cell265 and the third closed cell 273. The loops 249, 251, 253, 255, 257,259 may also be located on, for example, the second closed cell 269 andthe fourth closed cell 277. If additional loops are present, then theloops may be located on closed cells separated by one closed cell. Thisalternating structure may prevent twisting during expansion andcompression of the expansible support structure 261 that may damage ormisalign the guidewire lumens 243, 245, 247. Preferably, no loops 249,251, 253, 255, 257, 259 may be located on the fifth or proximal closedcell 281. The fifth closed cell 281 may be adhered to the main tri-lumenshaft 263. Thus, the fifth closed cell 281 may not fully expand duringexpansion of the expansible support structure 261 and may not beappropriate for holding loops 249, 251, 253, 255, 257, 259. Similarly,the fourth closed cell 277 may not fully expand and may also not besuitable for holding loops.

The expansible support structure 261, the guidewire lumens 243, 245,247, and the loops 249, 251, 253, 255, 257, 259 may initially be in acompressed state within a sheath 265 as described in previousembodiments. The sheath 265 may hold the expansible support structure261 in a compressed state. The sheath 265 may include a radiopaquemarker at a distal end of the sheath 265 or another known location alongthe sheath 265. The radiopaque marker may provide an indication of howmuch of the expansible support structure 261 is covered by the sheath265. This may allow for partial withdrawal of the sheath 265.

The expansible support structure 261 may be made of Nitinol or anothershape-memory material. The loop connectors 293 may also be made ofNitinol or another shape-memory material. The loop connectors 293 may beset to project inwardly from the cylindrical plane of the expansiblesupport structure 261 at a given angle. The angle may be any angle, butis preferably approximately 30 degrees inward from the cylindricalplane. The angle or the length of the loop connectors 293 or both may bevaried to create various positions of the guidewire lumens 243, 245, 247within the expansible support structure 261. The loops 249, 251corresponding to a guidewire lumen 243 may project in oppositedirections, for example, loop 249 may project in a distal direction andloop 251 may project in a proximal direction.

When the sheath 265 is withdrawn from around the expansible supportstructure 261, the expansible support structure 261 may expand to anexpanded state. The sheath 265 may be partially or completely withdrawnfrom the expansible support structure 261. During expansion of theexpansible support structure 261, the loops 249, 251, 253, 255, 257, 259may project inward from the cylindrical plane of the expansible supportstructure 261 to hold the guidewire lumens 243, 245, 247 in apredetermined position within the expansible support structure 261. Theguidewire lumens 243, 245, 247 may remain within the loops 249, 251,253, 255, 257, 259 during expansion and compression of the expansiblesupport structure 261. Also during expansion, the angle of theconnectors 285 relative to the closed cells may change. Placing theloops 249, 251, 253, 255, 257, 259 on closed cells separated by oneclosed cell may keep the guidewire lumens 243, 245, 247 from twisting.As the expansible support structure 261 expands, the guidewire lumens243, 245, 247 may diverge into predetermined positions. The expandedcatheter apparatus 241 may not block the vasculature.

Upon completion of a procedure, the expansible support structure 261 maybe compressed and withdrawn from the vasculature. The sheath 265 may beslid distally over the expansible support structure 261. Preferably, noparts of the catheter apparatus 241 extend outside of the cylindricalplane of the compressed expansible support structure 261 in thecompressed state to facilitate withdrawal of the catheter apparatus 241.

FIG. 13 shows another loop embodiment of an expansible structure 295. Incontrast to the loop embodiment 241 of FIGS. 12A-12C, the loopembodiment of the expansible structure 295 of FIG. 13 may have loops297, 299, 301, 303, 305, 307 attached on any of closed cell 309, 311,313, 315. The operation of the apparatus of the loop embodiment of theexpansible structure 295 is similar to the operation of the loopembodiment 241 of FIGS. 12A-12C.

To prevent twisting and damage to guidewire lumens 243, 245, 247,connecting members 317 may couple connection points 319 of struts 321 ona closed cell, such as 309, to connection points 323 of struts 321 on anadjacent closed cell, such as 311. The connection points 319, 323 arepreferably both distal or both proximal relative to the distal end ofthe catheter apparatus 295. The number and configuration of theconnecting members 317 may be variable. The connecting members 317 mayhave an upward bend 325 and a downward bend 327. The bends 325, 327prevent twisting and damage to the guidewire lumens 243, 245, 247 duringexpansion and contraction of the expansible structure 295. Duringexpansion and contraction of the expansible structure 295, the upwardbend 325 and the downward bend 327 cancel and lateral movement of theloops 297, 299, 301, 303, 305, 307.

The connecting members 317 of the expansible structure 295 may allowloops on each closed cell 309, 311, 313, 315. Loops 297, 299, 301, 303,305, 307 do not need to be on every other closed cell 309, 311, 313,315. The embodiment of FIG. 13 may provide for flexibility of theexpansible structure 295 and may facilitate expansion and contractionduring deployment and removal.

Although the foregoing description is directed to the preferredembodiments of the invention, it is noted that other variations andmodifications will be apparent to those skilled in the art, and may bemade without departing from the spirit or scope of the invention.Moreover, features described in connection with one embodiment of theinvention may be used in conjunction with other embodiments, even if notexplicitly stated above.

The invention claimed is:
 1. A catheter apparatus comprising: a catheterhaving a proximal end and a distal end; a first guidewire lumen and asecond guidewire lumen, the first guidewire lumen and second guidewirelumen at the distal end of the catheter; and a removable, expansiblesupport structure having a tapered proximal end and a longitudinal axis,the removable, expansible support structure allowing the first guidewirelumen and the second guidewire lumen to diverge upon expansion of theexpansible support structure, wherein the expansible support structureis self-expandable, and wherein, upon expansion, a distal portion of atleast one of the first guidewire lumen and the second guidewire lumenare substantially parallel with the longitudinal axis of the expansiblesupport structure.
 2. The catheter apparatus of claim 1, wherein thefirst guidewire lumen and second guidewire lumen diverge topredetermined positions.
 3. The catheter apparatus of claim 1, furthercomprising a retractable sheath surrounding the first guidewire lumenand the second guidewire lumen.
 4. The catheter apparatus of claim 3,wherein the retractable sheath is configured to expand the expansiblesupport structure.
 5. The catheter apparatus of claim 3, wherein theretractable sheath is withdrawn from around the removable, expansiblesupport structure to expand the removable, expansible support structure.6. The catheter apparatus of claim 5, wherein the retractable sheath isadvanced around the removable, expansible support structure to compressthe removable, expansible support structure.
 7. The catheter apparatusof claim 1, wherein the first guidewire lumen and the second guidewirelumen are coupled to the removable, expansible support structure.
 8. Thecatheter apparatus of claim 1, wherein the first guidewire lumen and thesecond guidewire lumen are positioned at a distal end of the removable,expansible support structure.
 9. The catheter apparatus of claim 1,wherein the first guidewire lumen and the second guidewire lumen arepositioned at least partially within the removable, expansible supportstructure.
 10. The catheter apparatus of claim 1, wherein the firstguidewire lumen and the second guidewire lumen are adapted to bepositioned eccentrically relative to an inner wall of an external lumen.11. The catheter apparatus of claim 1, further comprising a multi-lumenmain catheter shaft, wherein the first guidewire lumen and the secondguidewire lumen extend from a distal end of the multi-lumen maincatheter shaft.
 12. The catheter apparatus of claim 11, wherein thefirst guidewire lumen is contiguous with at least one of themulti-lumens of the multi-lumen main catheter shaft and the secondguidewire lumen is contiguous with at least one of the multi-lumens ofthe multi-lumen main catheter shaft.
 13. The catheter apparatus of claim1, further comprising one or more loops each corresponding to one of thefirst guidewire lumen and the second guidewire lumen, wherein the one ormore loops are coupled to the expansible support structure, and whereinthe one or more loops project inward toward an interior of theexpansible support structure.
 14. The catheter apparatus of claim 13,wherein the first guidewire lumen and the second guidewire lumen arethreaded through the corresponding one or more loops.
 15. The catheterapparatus of claim 13, wherein the one or more loops are coupled to theexpansible support structure by loop connections.
 16. The catheterapparatus of claim 1, wherein the removable, expansible supportstructure is non-implantable.
 17. The catheter apparatus of claim 1,wherein the first guidewire lumen and the second guidewire lumen extendat least to a distal opening of the removable, expansible supportstructure.
 18. The catheter apparatus of claim 1, wherein the removable,expansible support structure comprises nitinol or a shape-memorymaterial.
 19. The catheter apparatus of claim 1, wherein the removable,expansible support structure comprises closed cells, the closed cellscomprising zigzagged struts.
 20. A method for operating a catheterapparatus comprising: inserting the catheter apparatus according toclaim 1; diverging the first guidewire lumen and the second guidewirelumen by expanding the removable, expansible support structure.
 21. Themethod of claim 20, wherein the first guidewire lumen and secondguidewire lumen diverge to predetermined positions.
 22. The method ofclaim 20, further comprising a retractable sheath surrounding the firstguidewire lumen and the second guidewire lumen.
 23. The method of claim22, wherein the retractable sheath is configured to expand theremovable, expansible support structure.
 24. The method of claim 20,further comprising threading the first guidewire lumen through at leastone first loop and threading the second guidewire lumen through at leastone second loop.
 25. The method of claim 20, wherein the first guidewirelumen and the second guidewire lumen are positioned at a distal end ofthe removable, expansible support structure.
 26. The method of claim 20,wherein the first guidewire lumen and the second guidewire lumen arepositioned at least partially within the removable, expansible supportstructure.
 27. A catheter apparatus comprising: a catheter having aproximal end and a distal end; a first guidewire lumen and a secondguidewire lumen, the first guidewire lumen and second guidewire lumen atthe distal end of the catheter; a removable, expansible supportstructure having a tapered proximal end, the removable, expansiblesupport structure allowing the first guidewire lumen and the secondguidewire lumen to diverge upon expansion of the expansible supportstructure; and one or more loops each corresponding to one of the firstguidewire lumen and the second guidewire lumen, wherein the one or moreloops are coupled to the expansible support structure, and wherein theone or more loops project inward toward an interior of the expansiblesupport structure.
 28. The catheter apparatus of claim 27, the supportstructure further comprising a longitudinal axis and wherein, uponexpansion, a distal portion of at least one of the first guidewire lumenand the second guidewire lumen are substantially parallel with thelongitudinal axis of the expansible support structure.
 29. The catheterapparatus of claim 27, the expansible support structure furthercomprising struts and wherein the one or more loops are coupled to anintersection of struts.
 30. The catheter apparatus of claim 27, the oneor more loops further comprising loop supports coupling each of the oneor more loops to the expansible support structure.
 31. The catheterapparatus of claim 27, wherein each of the first guidewire lumen and thesecond guidewire lumen are configured to remain within the one or moreloops during expansion and compression of the expansible supportstructure.
 32. A catheter apparatus comprising: a catheter having aproximal end and a distal end; a first guidewire lumen and a secondguidewire lumen, the first guidewire lumen and second guidewire lumen atthe distal end of the catheter; and a removable, expansible supportstructure having a tapered proximal end and a longitudinal axis, theremovable, expansible support structure allowing the first guidewirelumen and the second guidewire lumen to diverge upon expansion of theexpansible support structure, wherein the removable, expansible supportstructure comprises closed cells, the closed cells comprising zigzaggedstruts, and wherein, upon expansion, a distal portion of at least one ofthe first guidewire lumen and the second guidewire lumen aresubstantially parallel with the longitudinal axis of the expansiblesupport structure.